Recent advances in biology and medicine have led to the development of laser beam microsurgery on cells. The laser beam is well adapted to micromanipulation of small objects, such as single cells or organelles. It provides the advantage of non-contact ablation, volatilization, sterilization and denaturing, cutting, and other forms of thermal and actinic-light treatment. The four parameters of focal spot size, laser wavelength, pulse duration, and laser power, provide a variety of regimes suitable for different applications.
One example of a use of laser beam microsurgery is the application of laser beams to the treatment of a mammalian oocyte and embryo. However, laser beam microsurgery in a number of inverted or upright microscopes can be utilized for many different surgical or medical applications.
In accordance with commonly practiced methods of laser beam microsurgery, the person conducting the microsurgery watches a screen displaying the sample and an indication of where the laser beam would be applied on the sample. Sometimes, a plurality of isothermal contour rings can be provided to demonstrate the range of thermal effects of the laser beam. Examples of such heat rings are provided in U.S. Pat. No. 7,359,116 and U.S. patent application Ser. No. 11/764,064.
Combining an objective, a laser and a directional beam to provide a visible indication of the targeting of the invisible laser beam has been proposed in U.S. patent application Ser. No. 12/481,363, filed on Jun. 9, 2009, now U.S. Pat. No. 8,149,504. However, the structure of these laser objectives lead to interference problems with the turret geometry of certain microscopes. Accordingly, a self-contained modular objective that eliminates such interference issue would be desirable.